The role of several genes essential for the development and function of the eye was studied. The homeobox gene, Prox 1 was mapped to mouse chromosome 1 close to the locus of the known retinal degeneration mutation, rd3. It was shown that the splicing pattern of Prox 1 mRNA as well as the distribution of Prox 1 protein are different in retinas from wild-type and rd3 mutant mice. However, no changes were found in the protein coding sequence of the Prox 1 gene in rd3 mutant. Several zebrafish mutants having altered patterns of Prox 1 expression in the developing muscle cells but not in the eye were identified. The Prox 2 gene was identified in human and mapped to chromosome 14q24.3. It was shown that in all vertebrates studied (human, mouse, chicken, zebrafish), there is a family of genes related the to Drosophila eyes absent gene consisting of at least 3 members. A gene related to Drosophila dachshund was identified in human and mouse. The possible involvement of Pax-6 in the regulation of the eyes absent and dac genes as well as the function of these genes are being investigated using different experimental approaches.